A truck mounted wireline logging unit is typically used to raise or lower multitudinous downhole logging tools for wells drilled on land. For offshore locations, the wireline unit is typically mounted on a skid. The wireline unit normally includes a cable spooled on a drum, means for controllably measuring that cable as it is placed in a well borehole, and means for providing power and signal connections onto the cable. There are certain downhole tools which require only a single conductor. Many tools, however, require seven conductors along the armored logging cable. The wireline cable must operate any number of tools including small diameter tools, large diameter tools, those which run in open holes, those operative in cased holes, and those up to seven conductors. The present disclosure is directed to a cable head supporting a seven pin connector which routinely mates with different types of logging tools having similar reciprocating connectors affixed thereto.
Such a connector must overcome certain difficulties. To be universally usable, it is necessary to place seven conductors in the armored logging cable, and to that degree complexity is increased even when only one conductor of the seven is used. Service of the equipment is an important factor, especially so, service is important when switching over to one logging cable connection to another. In a typical armored cable, there are multiple layers of armor wires wrapped around the core and conductors; it is therefore difficult, sometimes impossible to seal around the bundle of wires without substantial time and effort. Moreover, in view of the fact that a wireline unit is typically used at a remote field location, field repairs are essential either for switching connections or to solve field maintenance problems. This prevents the use of elaborate sealing techniques, and prevents soldering because it is difficult to accomplish accurately in the field. Moreover, field repairs or field connection modifications are always accomplished under the pressure of time because delay is expensive in drilling rig rental costs.
Consider, as an example, switching from one kind of logging tool to another. In disconnection of the first logging system, one must first loosen and remove the thrust collar of the cable head to expose the rope socket and the various boots which surround the individual signal conductors. Each individual boot must be disconnected from the appropriate feedthrus which communicate through the pressure separation bulkhead. The various boots need to be reconnected to the mating equipment on the next logging tool downhole instrument. Moreover, the mechanical linkage between the wireline and the tool must be first interrupted and then reconnected on the new tool. These procedures are not promptly done, and can last up to two hours depending on practice and experience of the field personnel. It is even more difficult to accomplish in inclement weather. Moreover, it must be tested to assure that the electrical conductors, being (up to seven in number) are correctly connected through the equipment. It must be kept in mind that one conductor may be required to transmit a millivolt signal while another conductor may be required to transmit currents for operation of 100 amperes or more.
The present disclosure is directed to a uniform termination for a wireline which encloses a rope socket, seven boots and mating sockets for handling seven electrical conductors are appropriate feedthrus. The boots mate to the feedthrus in a enclosing connector housing. The feedthrus in the connector housing are arranged in a specified pattern so that a set of plugs protrudes on the other side of the feedthrus, defining multiple pins in a connector. The rope socket and the related boots are surrounded by a split sleeve. Stress relief is obtained in a stinger which spreads the cable load into the cable end fitting. The mating apparatus must conform in pin location and coacting members so that they are connected together and separated. This defines a structure which can be used to accomplish connection to a wide variety of downhole logging instruments.
The present disclosure thus illustrates and depicts a universal cable head adapted to be located on the end of a wireline constructed with the typical armor wraps around seven conductors including a core member. It will be described hereinafter as the universal cable head. The stinger is constructed with the typical strength member or load carrying member and has a stress relief stinger around the exterior. It terminates at the universal cable head which is adapted for connection to a mating tool mounted connector or a cable electrode. By placing mating cable heads on logging tools, a quick disconnect system is thus devised. More importantly, it is able to connect and disconnect without requiring any disassembly whatsoever of the components within the universal cable head. The multiple conductors terminate in feedthrus which easily connect where connection is accomplished so that axial loading on the cable head is handled in the intended fashion.
Briefly, the present apparatus incorporates a universal cable head having a stress relieving stinger fastened around the lower end of the armored logging cable. The armored logging cable terminates with a woven armored cable within multiple wraps of armor wire thereabout. Seven conductors are normally included and are terminated within a male connector housing with a transverse bulkhead. An appropriate set of feedthrus mounted on the bulkhead is included, the male plugs preferably being a central ground and seven feedthrus for conductors. They are held in a fixed pattern within the housing. Moreover, the housing completely surrounds them and provides a uniform mode of connection. There is a rotatable sleeve about the housing which can be rotated to accomplish threading. Threading is accomplished with the mating member to be described. In summary, a universal termination is developed for use in a downhole environment for connection to enable logging tools of any size in open or cased hole to be connected, and to provide up to seven conductors with a ground.